Average U.S. rates on 30-year and 15-year fixed mortgages this week fell to fresh record lows for the sixth straight week. Cheap mortgages continue to help boost prospects for home sales this year.

Mortgage buyer Freddie Mac says the average rate on the 30-year loan dropped to 3.67 percent. That's down sharply from 3.75 percent last week and the lowest since long-term mortgages began in the 1950s.

The 15-year mortgage, a popular refinancing option, declined to 2.94 percent. That's down from 2.97 percent last week.

Rates on the 30-year loan have been below 4 percent since early December. The low rates are a key reason the housing industry is showing modest signs of a recovery this year.